In general, a load sensor is provided on a lower side of a vehicle seat. Since a sitting state of an occupant is detected on the basis of a seat load which is detected by the load sensor, safety measures are performed such as prompting the occupant who is sitting in the vehicle seat to fasten a seat belt or changing a development control of an air bag depending on the occupant.
In addition, for example, an occupant detection apparatus disclosed in JP 2008-18863A (Reference 1) does not detect the sitting state based on the seat load in a case in which a sum of a change amount (absolute value) of the seat load detected by a plurality of the load sensors is equal to or more than a predetermined threshold. Further, an occupant detection apparatus disclosed in JP 2005-233821A (Reference 2) detects the sitting state in only a case in which the detected seat load is in a predetermined range which is set in advance. Accordingly, accuracy at the time of detecting the sitting state is increased, and reliability thereof is improved.
However, usually, the load sensor provided on the lower side of the vehicle seat detects the seat load based on the pressure to the vehicle seat which is applied downward when the occupant sits down. For this reason, in a state in which a foreign material is pinched on the lower side of the vehicle seat, there is a problem in that an accurate seat load is not easily detected. Accordingly, there is a concern that an error occurs in a result of the detected sitting state, and thus, there is room for improvement on this point.